Radio Kisekya said at least 15 people had been injured in two days of demonstrations north of the capital.

U.N. police sent reinforcements Tuesday but had no reports of injuries, police spokesman Jean-Francois Vezina said.

Rampant disorganization and allegations of fraud hang over Sunday's critical vote for president, a third of the Senate and all of the lower house.

The winner of the presidential race will have to deal with Haiti's crushing poverty, a cholera epidemic that has killed more than 1,700 people and post-earthquake reconstruction — including overseeing billions of promised aid dollars from the United States and other nations.

Violent protests that caused several deaths occurred across northern Haiti before the election, fed by suspicions shared by public health experts that the cholera epidemic was caused by a contingent of U.N. peacekeepers.

While votes were still being cast Sunday, nearly all the major presidential candidates alleged government-backed hopeful Jude Celestin was benefiting from fraud and called for the election to be canceled. On Monday, however, leading contenders Mirlande Manigat and Michel Martelly backtracked and said the vote should stand.

Radio Kiskeya said that most of the people protesting Tuesday in St. Marc were supporters of Manigat. A powerful senator also led pro-Manigat protests farther north in Gonaives.

Haiti's provisional electoral council said problems were limited and called the election a success. Organization of American States observers acknowledged many voters had been disenfranchised by disorganization, intimidation and violence but called the vote valid.

But a delegation of U.S. Congress members led by Rep. James Clyburn of South Carolina voiced "serious concerns" about the election.

"We urge the U.S. government, the OAS and the UN to give full consideration to the charges of fraud and abuse and to await the result of any investigation before passing judgment on the conduct of Haiti's elections," the legislators said in a statement Tuesday.